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Spread spectrum communication method and system using diversity correlation and multi-user detection

a technology of multi-user detection and communication method, applied in diversity/multi-antenna system, polarisation/directional diversity, amplitude demodulation, etc., can solve the problems of large scale, complex process, and large size of phase-based electronically controlled phased array system, so as to ensure the separability of interfering signals, optimize the correlation process, and optimize the effect of the correlation process

Inactive Publication Date: 2008-11-20
LOT 41 ACQUISITION FOUND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

"The present invention provides a method and apparatus for processing spread-spectrum signals received by an antenna array using diversity parameters such as directionality, time, polarization, frequency, mode, spatial subchannels, and phase space. This allows separation of interfering signals and optimization of the correlation process. The invention also aims to reduce the number of antenna elements needed for array processing of spread-spectrum signals, and to exploit distortion in communication channels to enhance signal quality and increase system capacity for spread-spectrum communications. Additionally, the invention combines multi-user detection with the correlation process to improve frequency reuse in a spread-spectrum communication system. Other objectives include simplifying receiver designs, using true noise sources to encode information signals, and providing a bandwidth-efficient means of transmitting a decoding signal along with an information-modulated spread spectrum signal."

Problems solved by technology

These methods are complex processes and are more difficult to implement than tracking users in non-CDMA systems.
These changes may be the major obstacle for adaptive array deployment in the near future.
However, phase-based electronically controlled phased-array systems are relatively large, heavy, complex, and expensive.
This arrangement results in a system that is relatively lossy, electromagnetically sensitive, hardware-intensive, and has a narrow tunable bandwidth.

Method used

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  • Spread spectrum communication method and system using diversity correlation and multi-user detection
  • Spread spectrum communication method and system using diversity correlation and multi-user detection
  • Spread spectrum communication method and system using diversity correlation and multi-user detection

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Embodiment Construction

[0051]FIG. 1 shows a spread-spectrum receiver system of the present invention. An array 140 including at least two receivers 140.1 and 140.N receives a plurality of signals sn(t) from a plurality of directions of arrival, such as directions 61, 62, and 63, in a communication channel (not shown). Different directions (such as directions 61, 62, and 63) of arrival result in a plurality of different signal delays Δti occurring between signals received by the two receivers 140.1 and 140.N. Signal responses of the receivers 140.1 and 140.N are output at one or more receiver outputs, such as outputs 160.1 and 160.N. The receiver-output signals are coupled into a plurality of correlators 161, 162, and 163. The output of each correlator 161, 162, and 163 is coupled to a multi-user detector 103.

[0052]Three transmitted signals s1(t), s2(t), and s3(t) arrive at the array 140 from the directions 61, 62, and 63, respectively. This simple case is shown for the purpose of facilitating an understan...

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Abstract

A communication system transmits and receives a plurality of spread-spectrum signals having differences in at least one diversity parameter. The signals are highly correlated when their diversity parameters are similar, and the signals are uncorrelated when at least one diversity parameter is different Any combination of a transmitter, a receiver, and a communication channel may diversity-encode the signals to effect differences in their diversity parameters. A receiver diversity-decoder compensates for differences in a diversity-parameter of at least one received signal to make the signal highly correlated with at least one other received signal. A correlator combines at least two of the received signals to recover an embedded information signal. The communication system enables the use of true-noise signals for spreading information signals, provides simplified receiver designs, and enables antenna arrays to spatially process spread-spectrum signals.

Description

CROSS-SECTION TO RELATED APPLICATIONS[0001]This application is a divisional application of U.S. Application No. 09 / 824,264, filed Apr. 2, 2001, which is a continuation application of U.S. Provisional Patent Application No. 60 / 194,633, filed Apr. 4, 2000FIELD OF THE INVENTION[0002]The present invention relates to spread-spectrum communication and radar systems. More specifically, the present invention relates to a spread-spectrum communication system that uses a diversity-processing system, such as an antenna array.BACKGROUND OF THE INVENTION[0003]In a spread-spectrum communication system, the transmitted signal bandwidth is much greater than the bandwidth or rate of information being sent. Also, some function other than the information being sent is employed to provide the resulting modulated radio-frequency (RF) bandwidth.[0004]The desired signal is recovered by remapping the expanded-bandwidth signal into the original information bandwidth. In direct sequence CDMA (DS-CDMA) system...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H04B1/00H04B1/69H04B1/707H04B7/06H04L1/06H04L27/227
CPCH04B7/0613H04B2201/709709H04L1/0618H04L27/2278
Inventor SHATTIL, STEVE J.
Owner LOT 41 ACQUISITION FOUND
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